#import "CodePush.h"

@implementation CodePushDownloadHandler {
 // Header chars used to determine if the file is a zip.
 char _header[4];
}

- (id)init:(NSString *)downloadFilePath
operationQueue:(dispatch_queue_t)operationQueue
progressCallback:(void (^)(long long, long long))progressCallback
doneCallback:(void (^)(BOOL))doneCallback
failCallback:(void (^)(NSError *err))failCallback {
 self.outputFileStream = [NSOutputStream outputStreamToFileAtPath:downloadFilePath
 append:NO];
 self.receivedContentLength = 0;
 self.operationQueue = operationQueue;
 self.progressCallback = progressCallback;
 self.doneCallback = doneCallback;
 self.failCallback = failCallback;
 return self;
}

- (void)download:(NSString *)url {
 self.downloadUrl = url;
 NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:url]
 cachePolicy:NSURLRequestUseProtocolCachePolicy
 timeoutInterval:60.0];
 NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request
 delegate:self
 startImmediately:NO];
 if ([NSOperationQueue instancesRespondToSelector:@selector(setUnderlyingQueue:)]) {
 NSOperationQueue *delegateQueue = [NSOperationQueue new];
 delegateQueue.underlyingQueue = self.operationQueue;
 [connection setDelegateQueue:delegateQueue];
 } else {
 [connection scheduleInRunLoop:[NSRunLoop mainRunLoop]
 forMode:NSDefaultRunLoopMode];
 }

 [connection start];
}

#pragma mark NSURLConnection Delegate Methods

- (NSCachedURLResponse *)connection:(NSURLConnection *)connection
 willCacheResponse:(NSCachedURLResponse*)cachedResponse {
 // Return nil to indicate not necessary to store a cached response for this connection
 return nil;
}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
 if ([response isKindOfClass:[NSHTTPURLResponse class]]) {
 NSInteger statusCode = [(NSHTTPURLResponse *)response statusCode];
 if (statusCode >= 400) {
 [self.outputFileStream close];
 [connection cancel];
 NSError *err = [CodePushErrorUtils errorWithMessage:[NSString stringWithFormat: @"Received %ld response from %@", (long)statusCode, self.downloadUrl]];
 self.failCallback(err);
 return;
 }
 }
 
 self.expectedContentLength = response.expectedContentLength;
 [self.outputFileStream open];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
 if (self.receivedContentLength < 4) {
 for (int i = 0; i < [data length]; i++) {
 int headerOffset = (int)self.receivedContentLength + i;
 if (headerOffset >= 4) {
 break;
 }

 const char *bytes = [data bytes];
 _header[headerOffset] = bytes[i];
 }
 }

 self.receivedContentLength = self.receivedContentLength + [data length];

 NSInteger bytesLeft = [data length];

 do {
 NSInteger bytesWritten = [self.outputFileStream write:[data bytes]
 maxLength:bytesLeft];
 if (bytesWritten == -1) {
 break;
 }

 bytesLeft -= bytesWritten;
 } while (bytesLeft > 0);

 self.progressCallback(self.expectedContentLength, self.receivedContentLength);

 // bytesLeft should not be negative.
 assert(bytesLeft >= 0);

 if (bytesLeft) {
 [self.outputFileStream close];
 [connection cancel];
 self.failCallback([self.outputFileStream streamError]);
 }
}

- (void)connection:(NSURLConnection*)connection didFailWithError:(NSError*)error
{
 [self.outputFileStream close];
 self.failCallback(error);
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
 [self.outputFileStream close];
 if (self.receivedContentLength < 1) {
 NSError *err = [CodePushErrorUtils errorWithMessage:[NSString stringWithFormat:@"Received empty response from %@", self.downloadUrl]];
 self.failCallback(err);
 return;
 }
 
 // expectedContentLength might be -1 when NSURLConnection don't know the length(e.g. response encode with gzip)
 if (self.expectedContentLength > 0) {
 // We should have received all of the bytes if this is called.
 assert(self.receivedContentLength == self.expectedContentLength);
 }

 BOOL isZip = _header[0] == 'P' && _header[1] == 'K' && _header[2] == 3 && _header[3] == 4;
 self.doneCallback(isZip);
}

@end